Hello Brian, and welcome to the forum.
Reset the governor as per your initial instructions as this will start to play up when all else is running as it should,
I must concur with Bruce and AVB here, remove the filter, strip and clean the carby and and check your valve clearances cold, 0.15mm on the intake and 0.20mm on the exhaust.
Report back here once you're done and let us know how it all went.
Cheers, Ted
